Abstract
Anatase TiO2 (A-TiO2) usually exhibits superior photocatalytic activity than rutile TiO2 (R-TiO2). However, the phase transformation from A-TiO2 to R-TiO2 will inevitably happens when the calcination temperature is up to 600°C, which hampers the practical applications of TiO2 photocatalysis in hyperthermal situations. In this paper, high energy faceted TiO2 nanosheets (TiO2-NSs) with super thermal stability was prepared by calcination of TiOF2 cubes. With increase in the calcination temperature from 300 to 600°C, TiOF2 transforms into TiO2 hollow nanoboxes (TiO2-HNBs) assembly from TiO2-NSs via Ostwald Rippening process. Almost all of the TiO2-HNBs are disassembled into discrete TiO2-NSs when calcination temperature is higher than 700°C. Phase transformation from A-TiO2 to R-TiO2 begins at 1000°C. Only when the calcination temperature is higher than 1200°C can all the TiO2-NSs transforms into R-TiO2. The 500°C-calcined sample (T500) exhibits the highest photoreactivity toward acetone oxidation possibly because of the production of high energy TiO2-NSs with exposed high energy (001) facets and the surface adsorbed fluorine. Surface oxygen vacancy, due to the heat-induced removal of surface adsorbed fluoride ions, is responsible for the high thermal stability of TiO2-NSs which are prepared by calcination of TiOF2 cubes.
Highlights
Semiconductor photocatalysis has attracted much attention due to its potential applications such as water (Regmi et al, 2018; Xu et al, 2018) and air purification (Wen et al, 2015; Cui et al, 2017; Li et al, 2017a; Qi et al, 2017) and water splitting for clean H2 energy (Cheng et al, 2018) due to its peculiar chemical and physical properties
As a typical semiconductor photocatalyst, anatase TiO2 (A-TiO2) usually shows excellent photocatalytic activity. It usually transforms into poor photoreactive rutile TiO2 (R-TiO2) when calcination temperature is higher than about 600◦C, which hampers the practical applications of A-TiO2 in hyperthermal situations (Lv et al, 2011; Liang et al, 2017)
Photocatalytic oxidation of gasous acetone was used to evaluate the photocatalytic activity of the photocatalyst, which was performed in a 15 L reactor at ambient temperature under UV light irradiation. 0.3 g of the powder was firstly dispersed in 30 mL of double distilled water by sonicating treatment for 5 min
Summary
Semiconductor photocatalysis has attracted much attention due to its potential applications such as water (Regmi et al, 2018; Xu et al, 2018) and air purification (Wen et al, 2015; Cui et al, 2017; Li et al, 2017a; Qi et al, 2017) and water splitting for clean H2 energy (Cheng et al, 2018) due to its peculiar chemical and physical properties. As a typical semiconductor photocatalyst, anatase TiO2 (A-TiO2) usually shows excellent photocatalytic activity It usually transforms into poor photoreactive rutile TiO2 (R-TiO2) when calcination temperature is higher than about 600◦C, which hampers the practical applications of A-TiO2 in hyperthermal situations (Lv et al, 2011; Liang et al, 2017). There are many photocatalytically active stable TiO2-coated ceramic materials which are used for the control of organic contaminants, High Thermally Stable TiO2 Nanosheets including sanitary wares, bathroom tiles and self-cleaning glass. They require high processing temperatures and need excellent stability at high temperature (Periyat et al, 2009). The intensity for the lamp at working distance is measured to be 0.41 W/cm
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